Adaptation of Turbocharger to Small Displacement Single Cylinder SI Engine

This paper represents the adaptation of turbo charger to single cylinder 450cc SI engine which is used for the student formula competition. The experiment and 1D engine simulation called as GT-Power were performed to confirm the effect of valve profile, compression ratio and air fuel ratio on the engine performance under the naturally aspirated condition. The maximum valve lift of the intake valves increased 27% and that of the exhaust valves increased 15% as compared with the low profile cam. The compression ratio was increased from 12.3 to 13.5 by changing the piston top land length in order to improve the thermal efficiency. It was confirmed that the torque peak was moved from 6000 rpm to 8000 rpm by changing the valve profile. Furthermore, turbo charger was adapted to the engine as changing the capacity of the turbocharger, the maximum boost pressure and the air fuel ratio. The capacity of the turbocharger was changed with expansion and contraction of the performance map of RHF25 manufactured by IHI Corporation. The genuine capacity of RHF25 worked along the better operation line in the compressor at all engine speed ranges. The intake pressure of 2.0bar abs worked along better operation line in the compressor and showed the reasonable pressure ratio of the turbine. The temperature at the entrance of the turbine shows the maximum value under the stoichiometric mixture condition, and it became lower as the rich mixture condition. As a result of the analysis, the maximum torque was improved about 7.7% at 8000 rpm and the maximum power was improved about 29.5% at 10000 rpm compared with the naturally aspirated condition by adapting the turbocharger to the single cylinder SI engine.